Recognition of novel metal-resistant microbes and their potential resistance mechanisms in metal mines

Metal-resistant microorganisms are important resources for the remediation of metal-polluted environments, but common methods support only limited acquisition of resistant strains and elucidation of resistance mechanisms. In this study, we used metagenomic binning and assembly to identify potential metal-resistant microorganisms and explore the active mechanisms in a naturally restored metal mine wasteland. The results demonstrated that particular metals, including copper (Cu), lead (Pb) and chromium (Cr), impacted community composition; specific microorganisms can influence metals in the environment. Overall, 51 novel metal-resistant metagenome-assembled genomes (MAGs) were obtained through binning and assembly, 16 of which were effectively resistant to Cr, Pb and Cu. Sixteen key MAGs belonged to three phyla, namely Acidobacteriota, Desulfobacterota_B and Proteobacteria, and nine genera, with the majority representing unidentified species. These MAGs have diverse functions related to transfer and transportation, contributing to reducing metal bioavailability. As the 16 key MAGs included 23 mobile genetic elements, active horizontal resistance gene transfer was demonstrated by the high abundances of integrase, ist and transportase genes in the initial polluted environment. These results report novel taxa of a strain with resistance genes and its metal resistance mechanism, providing the necessary premise for subsequent functional verification and application.